The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Electronic devices such as computers, laptops, personal video recorders (PVRs), MP3 players, game consoles, set-top boxes, digital cameras, and other electronic devices often need to store a large amount of data. Storage devices such as HDDs may be used to meet these storage requirements.
Referring now to FIG. 1, a HDD 10 includes a hard disk drive assembly (HDA) printed circuit board (PCB) 14. A buffer module 18 stores data that is associated with the control of the HDD 10. The buffer module 18 may employ SDRAM or other types of low latency memory. A processor 22 is arranged on the HDA PCB 14 and performs processing that is related to the operation of the HDD 10. A hard disk drive controller (HOC) module 26 communicates with an input/output interface module 24 and with a spindle/voice coil motor (VCM) driver module 30 and/or a read/write channel module 34. The input/output interface module can be a serial interface module, a parallel interface module, a serial Advance Technology Attachment (ATA) interface module, a parallel ATA interface module and/or other suitable interface module.
During write operations, the read/write channel module 34 encodes the data to be written by a read/write device 59, as described in detail hereinbelow. The read/write channel 34 processes the signal for reliability and may include, for example error correction coding (ECC), run length limited coding (RLL), and the like. During read operations, the read/write channel module 34 converts an analog output of the read/write device 59 to a digital signal. The converted signal is then detected and decoded by known techniques to recover the data written on the hard disk drive.
A hard drive assembly (HDA) 50 includes one or more hard drive platters 52 that include a magnetic coating that stores magnetic fields. The platters 52 are rotated by a spindle motor 54. Generally the spindle motor 54 rotates the hard drive platters 52 at a fixed speed during the read/write operations. One or more read/write arms 58 move relative to the platters 52 to read and/or write data to/from the hard drive platters 52. The spindle/VCM driver 30 controls the spindle motor 54, which rotates the platter 52. The spindle/VCM driver 30 also generates control signals that position the read/write arm 58 by using mechanisms such as a voice coil actuator, a stepper motor, or any other suitable actuator.
A read/write device 59 is located near a distal end of the read/write arm 58. The read/write device 59 includes a write element such as an inductor that generates a magnetic field. The read/write device 59 also includes a read element (such as a magneto-resistive (MR) element) that senses the magnetic field on the platter 52. The HDA 50 includes a preamp module 60, which amplifies analog read/write signals.
When reading data, the preamp module 60 amplifies low level signals from the read element and outputs the amplified signal to the read/write channel module 34. While writing data, a write current is generated that flows through the write element of the read/write device 59. The write current is switched to produce a magnetic field having a positive or negative polarity. The positive or negative polarity is stored by the hard drive platters 52 and is used to represent data.